The War: No Easy Formula

U.S. military planners call it "the red
envelope." Shaped like a triangular flap, the 10,000-sq.-mi. zone
encompasses the industrial heartland of North Viet Nam (see map). Yet,
as though sealed off by an invisible cordon, its cluster of strategic
installations around Hanoi and Haiphong has hardly been grazed by the
war, for the U.S. has proscribed bombing raids on the trianglesave
for some Soviet SAM missile sites and a few minor targetsever since
its day-in, day-out raids against the North began last February.